Fix some _M_AMD64 checks in GSdx.

In the future these will be _M_X86_64, but for now this won't be the case.

plugins/GSdx/GPUDrawScanlineCodeGenerator.cpp

@@ -33,10 +33,6 @@ GPUDrawScanlineCodeGenerator::GPUDrawScanlineCodeGenerator(void* param, uint32 k
 	: GSCodeGenerator(code, maxsize)
 	, m_local(*(GPUScanlineLocalData*)param)
 {
-	#if _M_AMD64
-	//#error TODO
-	#endif
-
 	m_sel.key = key;
 
 	Generate();